Sketch Reflections of Functions

# Sketch Reflections of Functions

GCSE(H)

Graphs can be reflected by applying negative values to a function.

If the negative value is applied before the function takes place, then the result is a reflection in the y-axis:

y=f(-x) will reflect the function y=f(x) in the y-axis.

If the negative value is applied to the result of the function, then the reflection will take place in the x-axis:

y=-f(x) will reflect the function y=f(x) in the x-axis.

## Examples

1. Sketch the graph of the function f(x)=3x+4. On the same graph, sketch f(-x). Label the graph.

2. A function is given by f(x)=3sin(x). The function returns a value of -3 when x=270º. Sketch the graph for f(-x) where 0 < x < 360.